Electroluminescent devices such as organic light emitting diodes (OLEDs) are becoming widely used in applications such as displays. A common configuration for such devices involves a plurality of overlapping component layers. At a minimum, standard OLEDs require two electrodes and an electroluminescent material contacting both electrodes. Holes and electrons are individually injected into the electroluminescent material from the electrodes, and recombine to release energy in the form of visible, UV, or infrared light. So-called “sandwich” device architectures involve a layer of electroluminescent material sandwiched between the two electrodes. In devices using such geometry, at least one of the electrodes must be transparent to allow photons emitted from the electroluminescent material to escape the device. Nevertheless, since light is emitted in all directions by the electroluminescent layer, such devices exhibit lower emission efficiency when emitted light is trapped in the device (e.g. by waveguiding).